The invention relates to a gear shaping machine for the production, or more precisely machining, of gear wheels with a motor-driven rotatable machine table for holding the work-piece and a thrust spindle with a tool fixed thereto, e.g. a cutting wheel, said thrust spindle being displaceable in a selective stroking and superimposed rotary motion, whereby the stroke position can be detected by a first measuring device arranged in the stroke drive.
With such gear shaping machines, the work-piece to be machined and the thrust tool perform a rotary motion during the production, or more precisely machining, of gear wheels. The rotation axes of the work-piece and of the cutting tool arranged on the thrust spindle are preferably arranged parallel to one another in the production of cylindrical work-pieces. A preferably linear stroking motion in the direction of the axis of the tool for the metal removal is superimposed here on the rotation of the thrust tool, i.e. the cutting wheel.
If gear wheels with spur toothing are being produced, the work-piece and the thrust tool are rotated to the same extent. If, on the other hand, gear wheels with helical toothing are being produced, a greater or lesser degree of additional rotation of the cutting wheel must take place depending on the helix angle of the toothing. Apart from the rolling-rotation, the cutting wheel must also perform an oscillating helical motion. This oscillating helical motion of the thrust spindle is forced by a helical guide in the embodiment according to the prior art. In the case of the gear shaping machines of the earlier design, these helical guides are designed as conventional sliding guides. Modern high-speed shaping machines, on the other hand, are equipped with hydrostatically mounted guides. These are largely wear-free and smooth-running, since mechanical friction is prevented. However, all helical guides have the drawback that only certain helix angles can be achieved therewith for the gear wheel to be produced. The usual gear shaping machines are equipped with a rigid helical guide. The following mathematical interrelationship emerges here for the helix angle that can be achieved with the gear wheel:       sin    ⁢                   ⁢    β    =                    m        n            ·      π      ·              z        0                    p      p0      
In this interrelationship, β is the helix angle, z0 the cutting wheel tooth number, mn the real pitch module and pz0 the lead of the helical guide.
It follows from this that the helix angle β on the work-piece is variable only in the area between the smallest and largest possible tool number of the thrust tool. Apart from this drawback, the whole drive train is in addition subject to play. Furthermore, it is elastically deformable. Various attempts have already been made in the past to provide, instead of the helical guides, more flexible drives for the rotary motion of the cutting wheel. Various solutions have been proposed, but ultimately have not led to satisfactory productivity and gear tooth quality.
The problem of the invention, therefore, is to provide a gear shaping machine of the known type, with which on the one hand desired gear tooth geometries of the gear wheels to be produced, or more precisely machined, can be arbitrarily set, whilst on the other hand a high gear tooth quality and a satisfactory productivity can be achieved in the production of gear wheels.